/*
 * Copyright (c) 2011-2012 Alexander Dubu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * o  Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * o  Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * o  Neither the name Axil nor the names of its contributors may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package axil.compiler.lexer;

import axil.api.extend.Source;


/**
 * A lexical token produced by the lexical analyzer. These exist only briefly
 * during the compilation stage.
 */
public abstract class Token implements Source {
	public enum Type {
		open,
		close,
		comma,
		identifier,
		literal,
		keyword,
		operator,
		units,
		EOF
	}

	private int source;
	private int line;


	protected Token() {
		source = 0;
		line = 0;
	}


	protected Token(Source source) {
		assert source != null;
		this.source = source.source();
		this.line = source.line();
	}


	/**
	 * Get the type of this token.
	 */
	public abstract Type type();


	public boolean is(Type type) {
		return this.type() == type;
	}


	/**
	 * Get the unique ID assigned to the source element, such as the module,
	 * function or script.  If the object lives outside of source code, then
	 * zero is returned.
	 */
	public int source() {
		return source;
	}


	/**
	 * Get the line number in the original source where this object resides.
	 * If the object exists outside of source code (such as the boolean keyword
	 * "true"), then zero is returned.
	 */
	public int line() {
		return line;
	}



	/**
	 * Return a string representation of this object. The string returned is
	 * never null. The string representation here may be used in error messages
	 * produced by the compiler, so make this script-friendly.
	 */
	public String toString() {
		return type().toString();
	}
}
